The USA were making money supplying Germany and the allies. When Japan bombed Pearl Harbour, the Americans had to get off their seats and join the war. WW1 was from 1914 to 1918, the USA got involved in 1917. WW2 was 1939 to 1945, the USA got involved in 1941. It's great to sit on your seat while everyone is fighting, then write in your history books that you saved the world and you won the war
